It’s a week from the first preview of “Troubadour” and a wad of creative energy is ricocheting inside the Alliance Theatre.

In one room, Radney Foster and Zach Seabaugh look over two pages of script changes with show director, and Jennings Hertz Artistic Director, Susan V. Booth.

Bush and Shaffer share a laugh at rehearsal, with director Susan V. Booth in the background.

Down the hall, Kristian Bush – he of Sugarland fame and the composer of music for the country-focused musical – sits at a small white table with actress Sylvie Davidson. He closes his eyes and tucks his chin to his chest as Davidson’s angelic voice croons the song “Silver Willows,” occasionally looking up to quietly guide her to go low or high on a verse.

“Perfect,” he says with a slight smile as her sweet voice tapers off.

Downstairs, playwright Janece Shaffer sits in a corner armchair with her laptop, surrounded by pieces of paper as she continues to tweak the script amid a parade of people entering and exiting the office.

This swirl of activity will soon coalesce onto one rotating stage when “Troubadour” opens Wednesday at the Alliance, where it will run through Feb. 12.

The simple description of Shaffer’s sixth premiere at the theater is this: It’s 1950s-era Nashville and legendary country singer Billy Mason (played by stately country stalwart Foster) is preparing to retire. His son Joe (the square-jawed Atlantan Seabaugh, a former contestant on “The Voice”) thinks he wants to follow in his father’s footsteps, but dad isn’t too happy about relinquishing the spotlight to his son, whom he views as a good kid, but barely talented.

When Joe meets hopeful singer-songwriter Inez (the aforementioned Davidson) and Russian tailor Izzy (the expressive Andrew Benator), an immigrant who wants to make garish country music outfits, he begins to find his true self on his music-laden path.

The larger picture, said Shaffer, is “about meeting those people who can help you become who you can’t even imagine for yourself yet. There’s a line in the play, ‘Sometimes people who have been knowing us our whole lives don’t know us at all.’ I believe in meeting the right people at the right time and it feels like the people (involved in the show) are the right people at the right time.”

Shaffer, who got the idea for “Troubadour” during a visit to the Country Music Hall of Fame as she perused the rhinestone and glitter-encrusted costumes of ‘50s-era country music stars, includes Bush in that qualification.

She met the ace songwriter – whose numerous hits with Sugarland include “Baby Girl,” “All I Want to Do” and “Want To,” while his solo career produced “Trailer Hitch” and “Light Me Up” – after a friend reminded Shaffer that she had Bush’s email address, procured when the friend sat next to him on a flight.

Shaffer thrilled to the idea of writing a musical with Bush and floated an email his direction.

Kristian Bush wrote the songs for “Troubadour” while his brother Brandon serves as musical director.

He immediately said yes.

Bush has written 16 songs for “Troubadour” – his brother Brandon serves as musical director for the production – and, despite having played stadiums and won Grammy Awards, acknowledges that the experience of helping craft a musical has been life-altering.

“In music, many times the music happens before you realize what the story is. In this creative exchange, the story happened before the music and that allows for a different tool that you use when you make the song. You don’t use a sledgehammer. You get closer to using a chisel and a toothbrush,” he said.

Bush has immersed himself in the process throughout the year and found a kindred spirt in Shaffer, with whom he has a playful, sibling-like rapport.

The past six months he’s stared at the question in one of Brian Eno’s “Oblique Strategies” in his living room: “Do the words need changing?”

Recently, Bush spent a few days in New York, absorbing as many musicals as possible (“The Color Purple” and “Falsettos” among them) for “due diligence” and found himself attuned to the “moment when I lost my attention, when I drifted. When am I yawning? When am I thinking about popcorn? The most important piece of when you make stuff is to be a fan of watching stuff.”

Of course, he and Shaffer have the ideal editor in Booth, who is working with Shaffer for the fourth time.

“Susan is the third leg of the tripod,” said Shaffer. “And there is nobody smarter about this stuff. There’s a real shorthand and a real trust.”

“You want her to drive the race car,” Bush adds with a laugh.

Booth, meanwhile, compliments both Shaffer’s story – “It’s a gift to produce a story like this that has such a wealth of open doors and windows for people to walk through” – and the astute casting, which in many ways parallels reality.

Booth and Shaffer have worked together several times.

“Radney has had an incredibly successful 30-year career in Nashville – being our King of Country Music is in his DNA,” Booth said. “And Zach is an 18-year-old rising star, still trying to figure out where he wants his career to go.”

Noted Bush, “They’re typecast in a weird way. You never look at them and go, ‘Huh?’”

It was mandatory that Bush felt the same about the music that Foster, Seabaugh and Davidson will present during the show.

The singing will take place in natural environments – performing during a concert, playing a song during a radio interview – and not, as happens in many musicals, while popping out to buy coffee or mopping a floor.

“The story is as true as the songs are – that’s what makes this thing feel like it’s bigger than us,” said Bush. “Country music without authenticity isn’t country music.”